Refinishing Engine Cases - page 2

Step 1: If you have the tools, confidence and a shop manual, I recommend that you work,with parts off the bike. Working with the pieces on the bench makes things go a bit easier. However, you can do a perfectly satisfactory job without touching a screw. By the way, you should remove the old paint outside in your driveway near a garden hose.

Commercial paint removers take off the remnants of the old clear coating. The OEM clear coat is tough, and you should buy a remover that attacks epoxy and modern automotive paints. I bought the can you see here at my local Standard Brands paint store. You should be able to get a powerful remover at any large hardware store; most will have several brands and the knowledge of which one is best for this application.

Be cautious: Paint remover can harm your skin and sight. Be sure to wear eye protection, rubber gloves and a long-sleeved shirt when you use paint remover - no kidding.

Clean the oil or grease off the part from which you are going to remove the paint. A rag and some solvent does nicely. Mask off any painted parts you wish to protect from the paint remover. Take care not to get the remover on any paint you want to retain.

With a one- or two-inch paintbrush, apply the paint remover, using a dabbing motion to get the remover into the crevices and to reduce the risk of slinging it all around your driveway. If you got a really powerful remover, the clear coating will immediately begin to bubble and lift from the surface of the metal. After a few minutes the remover will be spent, and you can wash it off with water and a stiff brush. There will probably be some spots of paint left in places; another application or two takes care of that.

Step 2: If the casting from which you have just removed the paint is extensively corroded, you will need more than Simichrome and a stout heart to straighten it out. A seriously corroded case can be wet-sanded with 400 or 600 wet-or-dry sandpaper and soapy water. However, before you decide to do this, you should make an attempt to polish the worst spot. You might be surprised at how bad the corrosion isn't.

Wet-sanding is very effective and can be successful - if you heed a couple of cautions. First, proceed slowly; don't try to use the sandpaper like a shovel. Move the paper with a circular motion and keep it wet with a water-and-soap solution. (The soap helps keep the paper from loading up.) Second, if the casting has become lumpy from the corrosion process, back the sandpaper with a wooden or hard-rubber block. If you don't do this, the finish will be wavy. Finally, do not let the sandpaper load up. If it becomes clogged, it leaves scratches that are too deep to polish out later.

Step 3: Modern mass-produced motorcycle parts are not polished; they are sanded with very fine sandpaper. You can beat the sheen of the original finish on the parts you restore.

There are many polishes on the market and many serve well. Those shown here-Mother's and Simichrome-as well as Blue Magic are my favorites. Mother's initially cuts very fast and then polishes with less effort than most others. Blue Magic can give an incredible mirrorlike surface with hand polishing. Be wary of any polish you have not tested; some have lumps in them that can deeply scratch the surface.

Heat is an essential part of polishing. Unless the aluminum becomes hot from the friction of rubbing it with a cloth loaded with polishing compound, it will never get really bright. When you apply. Mother's Mag Polish, Simichrome or Blue Magic to a very slightly damp cloth, do so sparingly. These and other similar polishing compounds have water in them, and most of that water must disappear before serious polishing takes place.

When you apply polish to the surface and start to rub it in (circular motions, please), the frictional heat evaporates the water. During this time the grains of abrasive are leveling the surface by removing the high spots. As the water disappears there is a dramatic rise in friction and temperature between the cloth and the surface being polished; you can feel this when it happens. That is the time to really lay on the effort. When heat and friction build, polishing starts. If you make the common mistake of adding polishing compound each time the last load begins to dry out and get hot, you will continue to grind away at the surface and never achieve a true polish.

You may want to take advantage of your drill motor and polish your bike's parts with a polishing wheel or disc. That's fine, but it is very easy to round corners and dig ditches in the surface this way, so I urge you to practice on some hard-to-see parts before you take on a clutch cover. I have used drill motors for polishing and prefer one of the woollike buffing discs instead of the traditional cloth wheel. The buffing disc is gentler and spreads the load over a greater area at any one time, making it more difficult to dig ditches in the finish.

   

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